Relatives of starfish, brittle stars are marine animals that can live up to five kilometres below the surface on the abyssal plain. Surviving on plankton, the deep sea creatures whip across the sea floor using their long arms to propel them or clamber across coral.

Part of a three-year national project to map Australia's sea foor, the results have allowed researchers including marine biologist Tim O'Hara to start drawing up a family tree for the species. It marks the first step in understanding exactly how brittle stars evolved.

Dr O'Hara said genetic sequencing revealed that modern brittle stars dated back to just before the Permian-Triassic extinction, a mass extinction 252 million years ago which obliterated 95 per cent of marine life.

"We will be able to answer some of the big questions. The DNA technology will allow us to really deliver on how and where these things come into being and how the Pacific Ocean is related to the Indian Ocean, so it's really the beginning of a pretty exciting 20 years for biologists," Dr O'Hara said.

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Brittle stars were selected for the study because, with more than 2000 types found in marine ecosystems worldwide, they are a valuable reference to plot evolution in diverse marine environments: from polar regions to the ocean's deep abyssal plains.

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"On land, we know where the rainforests are and where the heathlands are," Dr O'Hara said. "But we know very little about our marine environments."

Brittle stars can range in size from a metre in diameter to a few millimetres. Some live in sand, some in mud and some on corals.

Dr O'Hara said that despite their abundance and variety, scientists did not yet know, for example, how brittle stars found in Australian waters were related to those found in New Zealand waters - or how those living in deep seas were related to those in the shallows. For land animals this would be unheard of.

He said such significant knowledge gaps left authorities seriously hamstrung when trying to manage the globe's marine biodiversity.

But he said improvements in DNA sequencing technology combined with increased computing power significantly boosted the scientific value of museum collections, which could now be studied in finer detail than ever before.

"We've got these amazing collections but now we'll be able to do new things with them that will open up whole new chapters," he said.

Museum Victoria sent samples to a US laboratory where 425 genes from 50 brittle star specimens in its collection were sequenced. The findings are outlined this month in the journal Current Biology.